A large variety of munition items, e.g., anti-armor cluster munitions (ACMS) are formed with a cavity that is filled with a specific amount of explosive material during manufacture. Until recently, one conventional technique was to melt an amount of explosive material such as 70/30 Cyclotol or 60/40 Comp B explosive in a "kettle" and then have it poured into the empty munitions item, with provision for a certain amount of the explosive material to form a riser after the item is filled. As the poured explosive material cools within the munitions item it experiences some shrinkage and draws in some of the still molten material from the riser. Eventually the riser material is knocked off and collected for reuse or disposal. This technique is both wasteful and somewhat dangerous. The amount of riser material that is scrapped for each munitions item filled often is as high as 200%, and riser scrap as high as 270% has been experienced. Naturally, this represents a waste of product and energy and carries with it an inherent danger of accidents as the scrap has to be collected manually and transferred back to the kettle for remelting. Also, because the method requires much personal handling by relatively skilled operators it is both slow and expensive.
Initial experiments aimed at developing apparatus and methods for injection loading of molten explosive employed a vertical downward dispensation of a controlled volume of molten explosive into a munitions item held in a vertical attitude, somewhat similar to the action of a vertically held hypodermic syringe used by a doctor to inject a fluid into a body part. The particulate HMX had a tendency to settle out in front of the discharge valve in this apparatus and caused intermittent clogging of the valve. Thus, while this solution is capable of reducing riser scrap to approximately 10% with explosives such as 70/30 Cyclotol or 60/40 Comp B, it is unsuitable for use with a viscous explosive like Octol which is normally mixed with the particulate component HMX. Thus, although this technique results in a significant reduction in riser scrap, and has generated associated benefits, it is not suitable for use with certain explosives.
Further research and development led to the development of the apparatus and method of the present invention, which provides a user the facility to inject a controlled amount of virtually any meltable explosive, including mixtures containing particulates, into individual munitions items quickly, efficiently, and with the production of only a minimal amount of riser scrap.